If you are building a house in Mexico, plan on being there during the construction. If not, your house could turn out quite different than what you had planned. Be sure to get a good builder (albañíl). Ask friends and business acquaintances for recommendations, and make sure that the builder is being recommended because he is an experienced and reliable builder, not because he is a great guy.
Plan to visit the construction site at least once a day to check on progress. Mexican construction crews make decisions as the work continues, often ignoring blueprints (or, more likely if you are using an albañíl instead of an architect, sketches) that show the dimensions of windows and the placement of electrical outlets. When you are onsite, check progress and make yourself available to answer questions. Try not to micro-manage. Things in Mexico are done differently than they are in your country and if you've chosen a good construction crew, they know what they are doing. But you'll still want to keep an eye on things and correct any mistakes or misconceptions sooner rather than later.